1. Field of the Invention
The present invention relates to a seat having an occupant detecting function, and an occupant detection device.
2. Description of Related Art
Conventionally, a capacitance type occupant detection device is known as an occupant detection device for detecting an occupant seated on a seat of a vehicle. According to JP-A-11-11256, for example, a capacitance type sensor having an electrode is disposed on an upper surface of a seating portion of a seat, and whether an occupant is seated on the seat is detected based on a variation of a value of an electric current generated as a result of application of a voltage to the capacitance type sensor. In addition, in the publication of JP-A-11-11256, a control part for applying the voltage and for detecting the variation of the electric current value is provided on a lower surface of the seating portion.
However, as specified by the technology described in JP-A-11-11256, the capacitance type sensor is disposed at an upper part of the seating portion, and the control part is disposed on a front side of the seat under a seat cushion. Therefore, an extended portion for serving as an electric connection between the capacitance type sensor and the control part inevitably becomes long, and passes along a front end of the seating portion.
Since the occupant detection device is configured in the above-described manner, the extended portion passing along the front end of the seating portion may receive noise that is irrelevant to whether the occupant is seated on the seat. For instance, capacitance may vary with a change of a position of a body part of the occupant below his/her knee, which may reduce accuracy of the occupant detection.